ventilation and indoor air quality - property care€¦ · chart recreated from data by prof jan...

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Ventilation and Indoor Air Qualityevaluation of existing ventilation provision and how this can be

improved in homes

Presented by Ian Mawditt | May 2017 | University of Warwick

PCA Annual Conference 2017

Challenges, Changes and Opportunities in Property Care

PCA Annual Conference 2017 slide 2

▪ People spend more than 90% of their time inside controlled

environments (buildings and vehicles)

▪ Indoor environments have undergone fairly radical changes since

1970s

▪ +ve is improved thermal comfort through better insulation and

efficient heating

▪ -ve is the potential deterioration of IAQ – internal pollutants

increase as outdoor air supply rates decrease

▪ This problem is not specific to new build: older buildings subject to

retrofit may be similar, or at even worse risk of poor IAQ

Human comfort and IAQ


Work and Public Places13%

Industry8%

Travel5%

Outdoor7%

Liquid6%

Food8%

Home53%

▪ Most of our exposure to

pollutants during the course of

our lives occurs in our homes

Total pollutant exposure

over 70 years

▪ Via lungs (little choice)

▪ Via stomach (greater choice)

Chart recreated from data by Prof Jan Sundell, Tsinghua University Beijing


Sources: BRE; Building Sciences (RSK); Leeds Beckett University; ATTMA

≈ 25

≈ 40

≈ 75

≈ 100

≈ 95

≈ 85≈ 100

≈ 750

≈ 120K

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pre-1900 1900-1919 1920-1939 1940-1959 1960-1979 1980-1999 2000-2005 2006-2010 2011-2016

MEA

N A

IR C

HA

NG

E R

ATE

@5

0PA

YEAR OF CONSTRUCTION

Air permeability trends: house age

number in dataset


8 5 8 11 11 19 16 22

PERCENTAGE REDUCTION SEALING DURING RETROFIT (SINGLE DWELLING CASE STUDY)

Remaining Loft (cables/pipes/hatch)

Unsealed masonry (permeation) Joist penetrations

Ground floor Services

Old window units Around windows

Existing dwellings are becoming more airtight


▪ Sets minimum background air flow rates for

control of bio-effluents, and increased rates for

moisture control – both considered to be the

key pollutants in dwellings.

▪ Approved Document F – Ventilation (AD F),

2010 revision introduced key Part F change:

ventilation in homes now a notifiable service

Regulations and standards – Part F

▪ But 96% of new dwellings fail to meet these

minimum performance specifications(study of 80 homes carried out for DCLG 2016)


De-centralised MEV study – 100% failure

Site 1 Site 3 Site 4 Site 5 Site 6

Design 43.00 37.00 45.00 31.00 15.00

ZCH Measured 20.80 19.10 21.00 12.30 5.50

% of Required Duty 48 52 47 40 37

0.00

10.00

20.00

30.00

40.00

50.00

litre

s p

er s

eco

nd

Zero Carbon Hub: Ventilation in New Homes study


▪ CO2: a common metric for ventilation

effectiveness

▪ Existing guidelines differ according to

building type:

▪ 1000 ppm ≈ 7.5 l/s/person

e.g. office (non-adapted)

▪ 1800 ppm ≈ 3.5 l/s/person

e.g. home (adapted)

▪ Recent studies suggest “…ventilation

rates above 0.4 h-1 or CO2 below 900 ppm

in homes seem to be the minimum level to

protect against health risks…” Wargocki, P. The Effects of Ventilation in Homes on Health. Int. J.

Vent. 2013; 12, 101–118.

CO2 as a performance indicator


▪ Volume of available air: a fresh air reservoir

▪ A smaller reservoir with more people will

mean it will empty more quickly.

Occupant density and CO2 production

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2


Indoor pollutant Guideline concentration value Averaging Time

TVOC 300 µg m-3 8 hours

Carbon Monoxide (CO) 100 (87.29)

60 (52.37)

30 (26.19)

10 (8.73)

mg m-3 (ppm)

mg m-3 (ppm)

mg m-3 (ppm)

mg m-3 (ppm)

15 minutes

30 minutes

1 hour

8 hours

Nitrogen Dioxide (NO2) 288 (0.15)

40 (0.02)

µg m-3 (ppm)

µg m-3 (ppm)

1 hour

long-term

AD F: Performance criteria (gaseous pollutants)


▪ Radon represents around 50% of our annual

radiation dose

▪ It is the leading cause of lung cancer in non-

smokers

▪ Approximately 1100 lung cancer deaths

attributed to Radon each year

▪ Radon mitigation measures are fairly simple

to apply to new build – retrofit is likely to be

more tricky

▪ Go to: www.ukradon.org/information/ukmaps

for further information

Source: Public Health England / UK Radon

Indoor pollution sources: radon ingress

http://www.ukradon.org/information/ukmaps


Industrial

emissionsWind erosion

(agricultural

pollution)

Vehicle

emissions

Construction

and mining

Naturally occurring non-

biological particles

Pollen and

other

biological

particulates

Radon Moisture Methane

Building envelope: a protective air barrier(?)

© Diagram adapted from Liddament, M. AIVC


What happens when the system fails?


Evaluation Methods

1. Observational: walkthrough survey (all surveys)

▪ Compare provision with AD F guidance, e.g. correct number of trickle ventilators,

number of fans, door undercuts, functional tests, etc.

▪ Check installation for completeness, quality and maintainability, e.g. are ducts

connected, are they the correct size, and unobstructed, check filter condition, etc.

▪ Check extent of problem(s) with occupants and asses their understanding. Do they

use their provision? Is it too complex? Have they been offered guidance?

▪ Use your nose – do you ‘sense’ a problem? Moisture? Odour/staleness?

▪ Can you identify the source of problem? Can it be controlled / contained / removed?

▪ Assess fitness for purpose:

▪ Mechanical system – is it noisy? Less likely to be used

▪ Geometry – is it a single-sided dwelling with natural vent?


Always observe before measurement

▪ Measuring just to obtain a value will not

identify the root cause of the problem!

▪ Where is the air going to or coming from?…


30 l/s kitchen fan: measures 30 l/s – all’s good, right!


Two commissioning companies simply adjusted the fan speeds in an

attempt to get some measurable air flow through this MVHR

Why didn’t they inspect it!


Evaluation Methods (cont’d)

2. a) Measurements (all surveys)

▪ Measure floor area and volume

▪ Measure flow rates through system

1. b) Measurements (planned works or problem dwellings)

▪ Air permeability

▪ Measure air exchange rates

3. Monitoring (problem dwellings or sample for planned works)

▪ Data log temperature and RH for at least one week in living rooms and bedrooms

(and outside) or problem areas. CO2 may provide additional useful data

▪ Determine most significant pollutants that might be the cause and sample:

▪ Combustion (CO, NO2, SO2, etc.)

▪ Chemicals (VOC, HCHO, etc.)

▪ Particulates and biological (PMs, HDMs, moulds)


1.2

1.4

Understand your monitored results


C–E


▪ Every room in a building will have a rising and

falling demand for ventilation according to

occupancy, activities, etc

▪ The challenge for fixed speed systems is

selecting a rate of ventilation that best covers

all scenarios:

▪ Too high (for peak requirements) will lead

to over-ventilation, energy penalty and

potential comfort issues

▪ Too low (for energy efficiency or quieter

operation) may increase risk of poor IAQ

▪ It’s a guessing game and therefore minimum

rate needs to be set at a baseline ‘safe’ level

(e.g. AD F)

Full Demand Control Ventilation

Slide content courtesy Aereco © 2016

RH, CO2, VOC, etc


▪ If you can track the IAQ requirement then you can

ventilate to suit the specified criteria

▪ The capacity is available to ventilate for peak as and

when neededVariations de débit et d'humidité en salle de bain

28/01/08, F3, appart, n°16

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100

0 2 4 6 8 10 12 14 16 18 20 22

Temps (heures)

Humidité relative en %

Débit en m3/h

Full Demand Control Ventilation

Slide content courtesy Aereco © 2016

Decent quality systems will

be silent in operation, meaning

that full automation should be

possible without nuisance


And finally…

▪ “But this property was built before 1995, so the ventilation regs don’t apply to me”

▪ This does not stand in court, particularly if other works have taken place, e.g.

replacement windows

▪ AD F guidance is the absolute minimum – do not use ‘minimum’ as your target.

Where’s the capacity when you need it?

▪ Be informed, and inform your clients! – the risks are increasing: property and

health. Raise issues with your client if you find a problem

▪ Don’t go ahead with a plan if you believe it to be wrong or inappropriate –

challenge it. Suggest an alternative if you can (ask someone if you can’t)

▪ Encourage stewardship of an installation – someone should take responsibility

throughout to ensure successful commissioning and operation

▪ Is anyone offering guidance to end users? If so who? You have a duty of care.


Thank you

[email protected]

ventilation and indoor air quality - property care€¦ · chart recreated from data by prof jan...

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